Project 2: The Globe

by huaishup @ 6:30 am 2 February 2011

1. Overall
When talking about data visualization, most of the people will think of computer graphic visualization. However, from my view, this is only one of the possible ways to do it. Why not trying visualizing data in physical ways? People can not only see the visualization result, but can also touch and manipulate the visualization device, which could be really interesting.

In this project, I explores the physical/tangible way of visualizing data. Using a paper globe as the data media, people can learn the language of a certain area by spinning the globe and adjusting the probe.

2. Material

Arduino x1

WaveShield with SD card x1

Button x1

Speaker x1

Variable resister x2




3. Process

a. Prepare the paper globe
Using google images to download one LANGE size global map. Download a Photoshop plugin called Flexify 2 to revise the map images. Here is the tutorial. Plot the revised image, cut and glue.

b. Fix the variable resistor
Laser cut 4 pieces of round woods to fix the shape of the paper globe. May use extra timber to do so. Install one of the variable resistor to the bottom of the globe. See below.

c. Install all the other parts
Install another variable resistor as the probe which points to the globe. Lazer cut a seat for the probe and the globe. Hook up two different Analog Input pins with the Arduino and resistors.

d. Calculate the position
Spin the globe and alter the probe. Different position has different resistor value, which can be mapped to the sound track. Calculate the position and map the sound track.

e. Prepare the sound
Download the language sound from Google translate and store them in the waveshield.

4. Video

5. Code

#include "WaveUtil.h"
#include "WaveHC.h"
char decision = 0;
SdReader card;    // This object holds the information for the card
FatVolume vol;    // This holds the information for the partition on the card
FatReader root;   // This holds the information for the filesystem on the card
FatReader f;      // This holds the information for the file we're play
WaveHC wave;      // This is the only wave (audio) object, since we will only play one at a time
#define DEBOUNCE 100  // button debouncer
int mySwitch = 7;
// this handy function will return the number of bytes currently free in RAM, great for debugging!
int freeRam(void)
  extern int  __bss_end;
  extern int  *__brkval;
  int free_memory;
  if((int)__brkval == 0) {
    free_memory = ((int)&free_memory) - ((int)&__bss_end);
  else {
    free_memory = ((int)&free_memory) - ((int)__brkval);
  return free_memory;
void sdErrorCheck(void)
  if (!card.errorCode()) return;
  putstring("\n\rSD I/O error: ");
  Serial.print(card.errorCode(), HEX);
  putstring(", ");
  Serial.println(card.errorData(), HEX);
void setup() {
  // set up serial port
  putstring_nl("WaveHC with 6 buttons");
   putstring("Free RAM: ");       // This can help with debugging, running out of RAM is bad
  Serial.println(freeRam());      // if this is under 150 bytes it may spell trouble!
  //  if (!card.init(true)) { //play with 4 MHz spi if 8MHz isn't working for you
  if (!card.init()) {         //play with 8 MHz spi (default faster!)
    putstring_nl("Card init. failed!");  // Something went wrong, lets print out why
    while(1);                            // then 'halt' - do nothing!
  // enable optimize read - some cards may timeout. Disable if you're having problems
// Now we will look for a FAT partition!
  uint8_t part;
  for (part = 0; part < 5; part++) {     // we have up to 5 slots to look in
    if (vol.init(card, part))
      break;                             // we found one, lets bail
  if (part == 5) {                       // if we ended up not finding one  :(
    putstring_nl("No valid FAT partition!");
    sdErrorCheck();      // Something went wrong, lets print out why
    while(1);                            // then 'halt' - do nothing!
  // Lets tell the user about what we found
  putstring("Using partition ");
  Serial.print(part, DEC);
  putstring(", type is FAT");
  Serial.println(vol.fatType(),DEC);     // FAT16 or FAT32?
  // Try to open the root directory
  if (!root.openRoot(vol)) {
    putstring_nl("Can't open root dir!"); // Something went wrong,
    while(1);                             // then 'halt' - do nothing!
  // Whew! We got past the tough parts.
void loop() {
  //putstring(".");    // uncomment this to see if the loop isnt running
  if(digitalRead(mySwitch) == HIGH) {
    Serial.println("switch is ok");
    int spin = analogRead(5);
    int probe = analogRead(2);
    if(spin>=0 && spin<=576 && probe >=179 && probe <=276) {
    else if(spin>=85 && spin<=313 && probe >=35 && probe <=160) {
    else if(spin>=580 && spin<=780&& probe >=0 && probe <=142) {
    else if(spin>=980 && spin<=1023 && probe >=7 && probe <=22) {
    else if(spin>=980 && spin<=1023 && probe >=0 && probe <=7) {
    else if(spin>=1023 && probe >=47 && probe <=288) {
// Plays a full file from beginning to end with no pause.
void playcomplete(char *name) {
  // call our helper to find and play this name
  while (wave.isplaying) {
  // do nothing while its playing
  // now its done playing
void playfile(char *name) {
  // see if the wave object is currently doing something
  if (wave.isplaying) {// already playing something, so stop it!
    wave.stop(); // stop it
  // look in the root directory and open the file
  if (!, name)) {
    putstring("Couldn't open file "); Serial.print(name); return;
  // OK read the file and turn it into a wave object
  if (!wave.create(f)) {
    putstring_nl("Not a valid WAV"); return;
  // ok time to play! start playback;

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